Vortex dynamics in a Karman street behind a heated cylinder: defects and potentialities of acoustic diagnostics

Abstract

In hhis paper reports results of experimental study of defects arising in a Karman vortex street in a wake behind a heated cylinder by means of remote acoustic diagnostics. This technique proved to be efficient for finding defects in a periodic structure by asymmetric shape of spectral picks of scattered sound.

A vortex street behind a heated cylinder is a classical object for investigation of heat transfer in flows. Until recently, investigations of a flow around a heated cylinder and of heated bodies in general were focused on the dependence of averaged characteristics of heat transfer (e.g., Nusselt number) on Reynolds number and on other flow parameters: degree of turbulence, roughness, and cylinder elongation. Nowadays the Karman street attracts the attention of researchers involved in fluid mechanics as a sample flow for testing new ideas in mixing of impurity, chaotic dynamics and so on. Detailed information about spatio-temporal dynamics of velocity and temperature fields is needed for these purpose. In this paper we show that heating of a streamlined cylinder can substantially change the regime in a wake and evoke the transition from a laminar state to spatio-temporal chaos of defects.